Carrollton Foundation Experts connects homeowners and property owners looking at drilled bell-bottom piers in Carrollton, TX with an independent local foundation company that builds them.
A bell-bottom pier is a reinforced concrete pier cast in a drilled shaft with a flared base. The bell spreads the load across more soil and resists being lifted when expansive clay swells, which is why they appear in many North Texas engineering specifications.
Construction
- A shaft is drilled beside or beneath the foundation beam.
- A belling tool cuts the flared base at the bottom.
- Reinforcing steel is set and the shaft is filled with concrete.
- The concrete cures before carrying any load.
- The foundation is lifted on the piers and shimmed.
Where They Are Used
- Engineered repairs for larger houses
- Commercial and multifamily buildings
- Repairs where uplift from swelling clay is a concern
What to Plan For
- Time: curing adds days to the schedule.
- Room: drilling rigs need access, which can be hard on tight lots and in fenced backyards.
- Cost: usually more per pier than pressed concrete.
- Spoil: drilled soil must be hauled or spread.
Engineering and Permits
Drilled piers are usually part of an engineered plan. Ask for the drawings and specifications, and confirm that the contractor will pull the City of Carrollton permit, since the city states that all foundation repairs require one.
Questions to Ask
- What are the shaft diameter, depth and bell size?
- How will the shafts be inspected before concrete goes in?
- How long will the concrete cure?
- How will equipment reach the work area?
When an Engineer Specifies Them
Drilled bell-bottom piers are most often seen in Carrollton on engineered plans: larger houses, commercial buildings and repairs where an engineer wants piers designed to resist uplift from swelling clay as well as settlement. If a contractor proposes them without an engineer, ask why, and ask what diameter, depth and bell size they plan to use.
Designed by an Engineer
The City of Carrollton requires foundation repairs to be designed by a professional engineer, and drilled bell-bottom piers are a method engineers often specify for heavier loads. Expect the drawings to show the shaft diameter, bell size, minimum depth, reinforcing steel and pier spacing. The contractor builds to that design, and the city inspects when the work is finished.
What Install Day Looks Like
Each shaft is bored with a drilling rig, belled at the bottom, fitted with a rebar cage and filled with concrete. Lifting waits until the concrete has cured. In the meantime the yard holds open spoil and equipment, so plan for pets, kids and sprinkler schedules, and ask who restores the yard when the crew leaves.
Common questions
Why do bell-bottom piers take longer than pressed piers?
The concrete must cure before it can carry the house.
Are they worth the cost?
For some houses and soil conditions, especially when an engineer specifies them, yes. Ask why they are recommended for yours.
Can they be used inside the house?
It is possible but harder. Many plans use drilled piers outside and another method inside.
How much do they cost?
Usually more per pier than pressed concrete. Angi lists piers in general at about $1,000 to $3,000 each; ask for an itemized quote.
Do I get the engineering drawings?
You should. Ask for them and keep them with your warranty and permit records.
Do bell-bottom piers need inspection before the pour?
Ask how the shafts will be checked before concrete goes in, especially on engineered plans.